Acryloxy-containing organosilicon compounds or methacryloxy- containing organosilicon compounds (hereinafter referred to as (meth)acryloxy-containing organosilicon compounds) readily react with radical-polymerizing monomers such as methyl methacrylate and styrene and are therefore very useful as starting materials for copolymers deriving from these monomers and as modifiers of polymers produced from the aforesaid monomers.
Such (meth)acryloxy-containing organosilicon compounds are prepared by the addition reaction of SiH-containing organosilicon compounds with the corresponding (meth)acrylic acid esters of aliphatically unsaturated alcohols or aliphatically unsaturated phenols followed by isolation by distillative purification from the crude mixture as set forth in U.S. Pat. No. 3,258,477; Belgian Patent Number 613,466; and British Patent Number 949,126. However, distillative purification and isolation is highly problematic. Because (meth)acryloxy-containing organosilicon compounds of this type readily undergo radical polymerization in the presence of heat, the distillative purification step itself results in a radical-reaction-induced increase in degree of polymerization. As a result, it has been difficult to obtain highly pure (meth)acryloxy-containing organosilicon compounds in high yields. Accordingly, investigations have been carried out on the implementation of this distillative purification step by the addition to the aforesaid crude mixture of a polymerization inhibitor, for example, hindered phenols, amine compounds, quinone compounds, and so forth as set forth in Polymer, 26, 437, 1985, but these methods have not proven to be entirely satisfactory.
In the instant invention it has been discovered that specific metal halides provide exceptional stabilization of the crude mixture in the preparative method under consideration and actually prevent gelation during distillative purification. The present invention was achieved based on this finding.
It is an object of the present invention the introduction of a highly productive method for the high-yield preparation of (meth)acryloxy-containing organosilicon compounds.